1. Field of the Invention
The present invention relates to a hand pump or air pump, and more particularly to a hand pump or air pump including a handle foldable or collapsible between a compact folding structure and an opened working structure and arranged for allowing the handle to be solidly and stably and effectively actuated or operated by the user while in the opened working structure.
2. Description of the Prior Art
Typical hand pumps or air pumps comprise a tubular or cylindrical housing including a stand, such as a foldable or collapsible stand attached or mounted or secured to the bottom portion thereof for supporting the tubular or cylindrical housing in or at an upright status, and a handle, such as a foldable or collapsible handle attached or mounted or secured to the upper portion thereof for actuating or operating the piston to move in a reciprocating action within the tubular or cylindrical housing in order to pump and to generate the pressurized air and to supply the pressurized air out of the tubular or cylindrical housing.
For example, U.S. Pat. No. 6,485,264 to Wu, and U.S. Pat. No. 7,331,768 to Wu disclose two of the typical hand pumps or air pumps each comprising a tubular or cylindrical housing including a bottom stand and an upper handle.
However, the stand and the handle may not be folded relative to the tubular or cylindrical housing such that the typical hand pumps or air pumps may occupy a great size or volume or dimension that is no good and adverse for storing and transportation purposes.
U.S. Pat. No. 5,947,706 to Gapinski discloses another typical hand pump or air pump comprising a tubular or cylindrical housing including a foldable or collapsible stand attached or mounted or secured to the bottom portion thereof.
However, the handle also may not be folded relative to the tubular or cylindrical housing such that the typical hand pumps or air pumps may occupy a great size or volume or dimension that is no good and adverse for storing and transportation purposes.
U.S. Pat. No. 5,494,411 to Chuang, U.S. Pat. No. 6,464,477 to Wu, and U.S. Pat. No. 6,558,129 to Wang disclose several further typical hand pumps or air pumps each comprising a tubular or cylindrical housing including a foldable or collapsible handle attached or mounted or secured to the upper portion thereof for actuating or operating the piston to move in a reciprocating action within the tubular or cylindrical housing.
However, the foldable or collapsible handle is off center and unbalanced while in the opened working structure; i.e., the handle is located at one side of a supporting pivot shaft or axle, such that the user may not forcefully and effectively and suitably apply the force to actuate or operate the piston with the foldable or collapsible handle of the typical hand pumps or air pumps, and such that the typical hand pumps or air pumps may not be forcefully and effectively actuated or operated by the user.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional hand pumps or air pumps.